Photographic dye solution



Patented Sept. 15, 1953 UNITED STATES PATENT OFFICE No Drawing. Application December 22, 1947, Serial No. 793,327

14 Claims. (Cl. 106-287) This invention relates to, and it is an object to provide, improvements in the art of varying the printing qualities (or color) of a gelatin supported photographic image through controlled imbibition of a dye or dyes from a high viscosity solution through the agency of differences of osmotic pressures.

While the invention is described herein mainly in relation to the modification, by dye, of the density of an image of a gelatine type photographic negative in order to improve its printing quality, the invention is otherwise useful for controlled dye application to the emulsion of prints, diapositives, lantern slides, or the like.

It is also an object of the invention to provide novel processes, chemicals, and techniques to offset or nullify the undesirable side effects normally encountered in the application of dyes to photographic gelatin.

Ever since the introduction into photography of gelatino-silver bromide emulsions, photographers have sought some easy method of selectively increasing the densities of portions of their negatives in order to secure better printing balance or to change at will the contrast of areas within a negative.

The most acceptable approach to the problem was to add to the gelatin some stain or color which would hold back a portion of the printing light while permitting the desired amount of effective illumination to reach the printing paper.

For purposes of enlarging, such stain or color should be free of structure, and it should dye the gelatin uniformly and smoothly without mottling or fringing, and without disturbing the normal physical characteristics of the gelatin.

There has been available only one technique which was workable within the limits of com mercial practice. This consisted of the use of a water soluble dye made up in extremely dilute solution and applied with a small brush, the brush being wiped almost dry before being applied to the gelatin; the brush then being kept in constant motion in contact with the gelatin until it no longer gave up color. The process was then repeated. This slow and tedious method was continued until the desired depth of tone was reached. Only an experienced worker, continuing the process over a considerable period of time, could achieve anything approaching a uniform stain over a large area.

The reason for this painstaking process is that gelatin immediately takes up an aqueous dye solution and, if a. solution containing more than a trace of dye is used with the above outlined 2 technique, uniform tones are impossible to achieve.

It is thus an additional object of the invention to provide a liquid vehicle which will act as a satisfactory carrier for the dye, and as a restrainer of the rate of imbibition, while incorporating chemicals to control any undesirable side effects.

To this end investigation was made into the oXy-organic compounds of the nature of aliphatic dihydroxy alcohols (i. e. glycol, etc.

A simple aqueous dye-glycol solution was unsatisfactory for several reasons. The surface glycols), e. g. diethylene tension was too high for easy applications; the

solution retracted and would not hold a line; the imbibition rate was erratic; the gelatin formed a permanent distortion ring at the gelatin-solution atmosphere juncture; some of the glycol appeared to enter'the gelatin and required a prolonged period to evaporate; and the treated film distorted under the heat of the printing light,

producing serious Newtons rings in glass sandwich negative carriers.

Chemical additions were then provided which eliminated these undesirable effects.

The dye solution of this invention is red for best density regulation, is quickly applied, readily controlled, and instantly removed when the desired depth of color is obtained. The treated gelatin is smooth, tough,v and relatively scufiproof, and-when treated with the dehydratorcleaner-hardener which is part of the process and technique--is immediately ready for printing. The gelatin is harder, lies fiater, and shows less tendency to produce N ewtons rings in a glass negative carrier than before treatment. The time required to secure a moderate stain, stopping about 50% of the printing light, is no more than two minutes.

Another object of the invention is to provide a solution and process which leaves no chemical nor reaction by-product in the gelatin, which might in time deteriorate either the gelatin or the silver image.

It is a peculiar and important characteristic of the present dye solution that there is an interval following application to the gelatin during which little or no dye is transferred, and it is possible to so adjust the solution that the operator will have ample time in which to spread the solution over a considerable area and to work in the details of an irregular contour without sacrificing any uniformity in the dye deposit.

A further object of the invention is to produce a practical and reliable photographic dye solution and process, which are exceedingly effective for the purpose for which they are designed.

These objects are accomplished in the manner as will fully appear by a perusal of the following specification and claims.

Referring now to the details of the invention, the dye. formula comprises initially separate solutions, as follows:

Solution A Cc...v Dilute C. P. acetic acid, sp. gr. 1.040 33.5 Acetaldehyde (Acetaldehyde boils at'-69 Therefore, ingredients and utensils for.

this solution must be below 60 F.) l6 Diethylene glycol 2000' Make up 24 hours before use.

I Solution B Brilliant Scarlet 3R (C. I. 185, page 42) (National Aniline Division, Allied=Chemi cal 85 Dye Corporation) "grams; 100 Distilled water (boiling) cc 900 When 'cool, as cc 1000 A saturated solution, decant if necessary;

Solution Food, Drug, and Cosmetic Green No. 3 (Fast Green) (National Aniline Division, Allied Chemical & Dye-Corporation) grams Distilled water: (boiling) cc 980 When cool, qs cc 1000 Solution D Food, Drug, and CosmeticBlue No. 1 (National AnilineDivision, Allied Chemical 8:

Dye Corporation) grams 15 Distilled water (boiling) cc 980 When cool, qscc 1000 Solution E Cc- Distilled water .980. AerosolO'T, commercial 10% solution Make up several hours before use;

The above described, separate solutions. are combined in the. following amounts, with stirring; to produce the complete dye solution:

Cc. Solution A l. 180 solutionBf 60. Solution Ci 1'7 Solution D 12 Solutionlil 100 Bottle tightly and agitate" occasionally for twenty-four hours, and thereafter add:

Solution A 80 cc.

Cc; Is'opropyl alcohol-(pure) 500 Amyl acetate, purified 4 Acetaldehyde 10 Distilled water 20 Ingredients and utensils below 60 F.

The dehydratingcleaning hardening solution, andthe complete dye solution, are used in the process as now described.

The cleaning solution is applied to the gelatin surface of a negative, or the like, witha'pledget of cotton, the surface is mopped for thirty seconds or more, and then the solution is removed by bufiing with a dry pufi of cotton.

Thereafter the dye solution is flowed upon the surface of the gelatin with a soft brush of a size suited to the area to be covered. The dye solution is pooled and puddled over the area being dyed and it is left on the gelatin for a number of minutes predetermined by test .upon the particular material in use; such number of minutes giving a density of dye which will produce the desired elfect upon the image being treated. At the" end. of the predetermined interval the dye solution is squeegeed from the gelatin with a rollof cotton, no great care being necessary to avoid damaging the gelatin surface.

Then, the cleaning solution is again applied, in somewhat greater quantity, and after a minute or'more, isbuffed off. This bufling technique is important, as tests indicate that the hardening and conditioning ofthe gelatin .take place at the evaporating point;

stains are placed in the. gelatin, with increased moisture absorption; a second application of the dehydrator-cleaner-hardener is indicated, where- Thislatter effect is achievedthrough the wettingagent, Aerosol OT.

Viscosity-surface tension .is; controlled: by the relationship; diethylene.glycolewater-Aerosol OT. The. viscosity: must. be. sufficient to' prevent spreading.- The surface-tension must beat a minimum so thatth'eisolution willlieflat and not retract as the'gelatin' takes upthewater and changes the diethylene glycol-.-HzO balance.

The viscosity is supp-liedri by'the'diethylene glycol and the interacti'onof the other ingredients. The surface tension is reduced and controlled by the commercial Wetting agent, Aerosol'OT (sodium di-octyl sulfosuccinate). It should be noted here that somecontrol can be exercised'over the imbibitionrateby varying the diethylene glycol-Aerosol OT solution balance, but the variation must not be sufficient to destroy the good working qualities of the formula.

Acidity.--The pH of the'solution is controlled by'the acetic acid. Thepl-I must beheld within narrow limits close to the iso-electric point of gelatin (4.7). The pH of the completedye' solution is 4.43. This acidityeliminates edge distortion, prevents undue-swelling ofathegelatin and promotes uniform imbibitioniof the dyes; Theacetic acid exerts an unexplained control.

overthe buckling'tendency of the film under heat." Excess acid causes'creepingof dye. Insufficient acid does not control side efiects- Hardening and restraining agents.-None. of the gelatin hardening agents used in'the customary-practices of photography are suitable for the purposes-of this formula. As with the other ingredients (except the dyes), agent must be volatile, yet must be of sufficient stability for the practical purposes of storage and use. Acetaldehyde" polymers (aldol condensation), such'asparaldehyde or aldol, have-been The. cleaning solutions has: a pronounced dehydrating effectand where deep the hardening.

found by me to meet these requirements and are readily formed from the parent chemical in the solution. In the present embodiment it can be anticipated that an acetaldehyde-paraldehyde equilibrium will be set up, a buffering effect being ecured which, when disturbed, will release the highly volatile acetaldehyde from the more stable polymer. In addition to acting as a hardening agent, the acetaldehyde serves to reduce, and so control, the iinbibition rate. This latter effect is pronounced. An excess of aoetaldehyde stops the action altogether. It is therefore a critioal factor that the minimum amount of acetaldehyde which produces a satisfactory hardening is not great enough to unduly inhibit the imbibition rate. It has been found that certain esters have a pronounced hardening eifect upon gelatin, and this is true even though the ester has but a very limited solubility in water. Two of these are made use of in this process: amyl acetate and sodium di-octyl sulfosuccinate (aerosol OT). It is worth noting that a solution containing diethylene glycol, acetic acid and acetaldehyde, adjusted with water to the same dilution as is the final formula, does not temper the gelatin so satisfactorily as the complete solution containing the ester, Aerosol (3T) Nature of the dyes.-Suitable dyes are water soluble acid dyes, substantive to gelatin, which are compatible with the other substances in solution and which, when mixed for special spectral characteristics, must have identical capillarities under the conditions of use.

All of the chemicals outlined above combine to form a homogeneous, stable solution which, through osmotic pressure, transfers dye at a uniform, controlled rate into photographic gelatin, Whether that gelatin be the silver emulsion of a negative, or the anti-halo, non-curling gelatin backing of a negative, or the emulsion of a print or of a diapositive or lantern slide, whether of silver image or of its colored chemical reaction products, or of images in gelatin formed wholly or partly of dye or dyes.

It is apparent, therefore, that the process may be used to modify the colors of a colored film or a diapositive, or a colored print which carries the coloring materials in a gelatin medium, and that for such purpose the dye or dyes can be modified or substituted to meet specific requirements.

The dehydrating-cleaning-hardening solution serves a multiple purpose. Used prior to the application of the dye solution, it cleans the surface of the gelatin, removing grease and foreign material Which might interfere with the action of the dye. It brings about a change in the surface of the gelatin by producing a glass-like hardness which resists scufiing even when the gelatin has absorbed considerable water. It introduces a minute quantity of amyl acetate, a hydrophobic agent, which serves an important role in controlling the behavior of the dye solution at the gelatin-atmosphere juncture. This solution, used after the application of the dye solution, rapidly dehydrates the gelatin, further conditioning, and hardening it so that within a minute or two fOllOWll'lg its application the negative, diapositive, or print is ready for use. It serves further, when multiple applications of dye are to be made, to act as a controlling and inhibiting agent, so that dyed areas which may contain residual moisture do not take up the succeeding apl lications of dye at an uncontrolled rate.

From the foregoing description it will be readily seen that there has been produced a photographic dye solution and fills the objects of the invention as set forth herein.

While this specification sets forth the present and preferred details of the photographic dye solution and process, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claims.

The dye identified herein as F. D. & C. Green N o. 3 (Fast Green) (NAD), the last initials meaning National Aniline Division, is described on page 5 of the bool: entitled Coal-Tar Regulations of the Food 8: Drug Administration, said book having been issued September, 1940. The dye herein identified as F. D. & 0. Blue No. 1 (NAD) is described in the British Colour Index on page 171 and the dye is identified by the dye number 6'71.

Having thus described the invention, the following is claimed as new and useful, and upon which Lettes Patent are desired:

1. A stable dilute photographic dye solution for transferring a dye at a substantially uniform controlled rate into a photographic gelatin film, said solution having a pH close to the isoelectric point of gelatin and consisting essentially of a dilute aqueous solution of a dye, an aliphatic dihydroxy alcohol, acetic acid in amount capable of imparting to said dilute solution a pH of the order set forth, a wetting agent, and a hardening agent for the gelatin selected from the group consisting of acetaldehyde, paraldehyde, and aldol.

2. A stable dilute photographic dye solution for transferring a dye at a substantially uniform controlled rate into a photographic gelatin film, said solution having a pH close to the isoelectric point of gelatin and consisting essentially of a dilute aqueous solution of a dye, diethylene lycol, acetic acid in amount suilicient to give the solution the pH stated, a wetting agent, and a hardening agent for the gelatin selected from the group consisting of acetaldehyde, paraldehyde and aldol.

3. A stable dilute photographic dye solution for transferring a dye at a substantially uniform controlled rate into a photographic gelatin film, said solution having a pH close to the isoelectric point of gelatin and consisting essentially of a dilute aqueous solution of a dye, diethylene glycol,

oetic acid imparting to said dilute solution a pH,

of the order set forth, a wetting agent, and a hardening agent for the gelatin selected from the group consisting of acetaldehyde, paraldehyde and aldol.

i. A stable dilute photographic dye solution for transferring a dye at a substantially uniform controlled rate into a photographic gelatin film, said solution having a pH close to the isoelectric point of gelatin and consisting essentially of a dilute aqueous solution of a dye, diethylene glycol, a wetting agent, and acetic acid imparting to said dilute solution a pH of the order set forth.

5. A stable dilute photographic dye solution for transferring a dye at a substantially uniform controlled rate into a photographic gelatin film. said solution having a pH close to the isoelectric point of gelatin and consistin essentially of a dilute aqueous solution of a dye, diethylene glyool, acetic acid, acetaldehyde and sodium dioctyl sulfosuccinate acting as a wetting agent.

6. A stable dilute photographic dye solution for transferring a dye at a substantially uniform controlled rate into a photographic gelatin film, said solution having a pH close to the isoelectric process which substantially ful- 7 point of: gelatinzandloonsisting; essentiallyyof :a: dilute; aqueous solution: ofsaadye, diethylene rgly col, a wetting agent, acetic acid imparting tosaid:

diluteasolution :a. pH- .of :the :ordenset" forth, the

water content ofthe solution being less'than the diethylene glycol content.-

7. A stable dilute; photographic;dye-solutionn for: transferring j a dye at a. substantially uniform. 1

fontransferringa dye at a substantially uniform 1 controlled rate into a photographic gelatin film,v

said-solutionhaving .apI-I closeto the :isoelectric point, of. gelatin. and; consisting essentially of. a dilute aqueous solution; of a dye,:,diethylene glycol,L a wetting agent to reduce-- the surface tension ofthe solution, acetieacid imparting to said.

solutiona pH of-the order set forth, and acetaldehyde,-,saiol solutionthavinga slow hardening ;action on the gelatin;

9. A stable dilute photographic dye solution for transferring. a dye at' asubstantially uniform controlled rate into-a-photographic gelatinfilm, said solution having a 'pH close to the isoelectric point ofcgelatin and consisting essentially, of a dilute aqueous solution of .a dye, diethyleneglycol aceticacid imparting .to saiddilute: solution a; pH .of. the order set forth, a. wetting agent to. reduceith'esurface tension .of theisolution,v and a polymerofthe aldcl condensation, acting as a hardening agent for the gelatin.

10. A- stable dilute photographic dye solution for.-transferring adye .at a substantially uniform controlled: rate -.into a photographic gelatin .film, said solutionhavingazpl-l close to theisoelectric point :of.-:gelatin and consisting essentiallyofsa dilute aqueous solution of a dye, diethyleneglycol, acetic acid imparting to said dilute'solution a pI-Lofthe orderiset forth, a wetting agent to .reducethessurface tension of thesolution, andparaldehyde acting .as ahardening agent for the gelatin.

11; A-stable' dilute photographicdye solution, fortransferringadye at a substantially uniform controlledrateinto a photographic gelatin film; said solution having a p-H close to the isoelectric point-of gelatin and consisting essentially of a dilute aqueous solution of a dye, diethylene glycol, acetic'acid imparting to said dilute solution a pH'of-the order set forth, a wetting agent toreduce the surface tension of thesolution, and aldol acting as a hardening agent for the gelatin.

12. A stable dilutephotographic, dye solution.

foritransferringzardyer at-azsubstantially uniformcontrolled rateeinto a photographic gelatin film,

said solution-cconsisting essentially: of diethylene,

glycol, dilute. acetic acid, and. acetaldehyde, an.

' aqueous solution containinga.plurality of water soluble dyes of different colors, and a wetting agent,-said solution. havingthethree first named. constituents thereof insubstantially thefollowing proportions:

Volumes methylene-glycol 2000- Diluteaceticacid (5.1 g, about 1.040) 33.5 Acetaldehyde 16;

thevolume of water in-the solution being lessthan said volume of said glycol, and the amount" of said wetting agent bein sufiicient to substantiallyreduce the surface tension of said solution, and'the-amount of the acetic acid being enough to'gi-ve'the dye solution a pH of about 4A3.

18 A solution as'covered in claim 12,- in whichthe wetting iagent'issodium di-octyl sulfosuccinate:

14:.- A" photographic dye solution which is an admixture of the following in the-proportions stated:

. 260 volumes of a solution of- Dilute. C. P: acetic acid, sp. gr. 1.040 33.5 cc. Acetaldehyde 16- cc. Diethylene glycol .2000 cc. oovolumesof a solution of- Brilliant Scarlet 3R (0. I.. 185) (NAD) "-grams. Distilled water About 100cm.

such solutionbeing: stable, and 'being capable of transferring a-dye at a substantially uniform controlled "rate into a photographic gelatin film.

CLARENCE E.'PAYNE.

RefenencestCited in the file of this patent UNITED STATES PATENTS- Number- Name Date 1,582,136. Gustin Apr. 27, 1926' 1,652,949 MacGilvra Dec. 13, 1927 2,074,858... Rafio Mar. 23, 1937 2,272,117 Hasslacher Feb. 3, 1942. 2,433,811 Hail? Dec. 30, 1947 2,447,462 Harsh .Aug. 17, 1948 

1. A STABLE DILUTE PHOTOGRAPHIC DYE SOLUTION FOR TRANSFERRING A DYE AT A SUBSTANTIALLY UNIFORM CONTROLLED RATE INTO A PHOTOGRAPHIC GELATIN FILM, SAID SOLUTION HAVING A PH CLOSE TO THE ISOELECTRIC POINT OF GELATIN AND CONSISTING ESSENTIALLY OF A DILUTE AQUEOUS SOLUTION OF A DYE, AN ALIPHATIC DIHYDROXY ALCOHOL, ACETIC ACID IN AMOUNT CAPABLE OF IMPARTING TO SAID DILUTE SOLUTION A PH OF THE ORDER SET FORTH, A WETTING AGENT AND A HARDENING AGENT FOR THE GELATIN SELECTED FROM THE GROUP CONSISTING OF ACETALDEHYDE, PARALDEHYDE, AND ALDOL. 